in botany, "envelope of a flower," 1706, from French périanthe, from Modern Latin perianthium (17c.), literally "that which is round the flower," from Greek peri "around, about" (see peri-) + Greek anthos "flower" (see anther). Related: Perianthal.

"membranous sac which encloses the heart," early 15c., from Medieval Latin pericardium, Latinized form of Greek perikardion "(membrane) around the heart" (Galen), from peri (prep.) "around, about" (see peri-) + kardia "heart" (from PIE root *kerd- "heart"). Related: Pericardiac.

Athenian statesman (c. 495-429 B.C.E.), leader of the city in its period of intellectual and material preeminence, from Latinized form of Greek Perikles, literally "far-famed," from peri "all around" (see peri-) + -kles "fame," a common ending in Greek proper names, related to kleos "rumor, report, news; good report, fame, glory," from PIE *klew-yo-, suffixed form of root *kleu- "to hear." Related: Periclean.

"an extract, a selection from a book," especially "a passage of Scripture appointed to be read on certain occasions," 1650s, from Late Latin pericope "section of a book," from Greek perikopē "a section" of a book, literally "a cutting all round," from peri "around, about" (see peri-) + kopē "a cutting" (see hatchet).

"point at which a celestial body is nearest the Earth," 1590s, from Modern Latin perigeum (15c.), from Late Greek peregeion, used by Ptolemy as a noun, properly neuter of adjective perigeios "near the earth," from peri ges, from peri "near" (see peri-) + ges, genitive of gē "earth" (see Gaia). Now only of the moon, formerly used also for the corresponding point in the orbit of any celestial body. Compare apogee.

"point at which a planet or comet is nearest the Sun," 1680s, coined in Modern Latin (perihelium) by Kepler (1596) from Latinizations of Greek peri "near" (see peri-) + hēlios "sun" (from PIE root *sawel- "the sun"). Subsequently re-Greeked.

early 15c., perimetre, "circumference, outer boundary, or border of a figure or surface," from Latin perimetros, from Greek perimetron "circumference," from peri "around, about" (see peri-) + metron "measure" (from PIE root *me- (2) "to measure"). Military sense of "boundary of a defended position" is attested by 1943. Related: Perimetric; perimetrical.

"of or pertaining to the period just before and just after birth (commonly reckoned at from 1 to 4 weeks before and after birth), 1952, from peri- + natal.

also perinaeum, "the region of the body between the anus and the genital organs," early 15c., from Medieval Latin perinaeon, Late Latin perineum, from Greek perinaion, perinaios, in medical writing, "space between the anus and the scrotum," also, in plural, "male genitals," said to be from peri "near" (see peri-) + inan "to empty, carry off by evacuation," a word of unknown origin. Beekes says the notion is "the empty region," which would bring it near to the modern jocular name, taint. Related: Perineal.

early 15c., periode, "a course or extent of time; a cycle of recurrence of a disease," from Old French periode (14c.) and directly from Medieval Latin periodus "recurring portion, cycle," from Latin periodus "a complete sentence," also "cycle of the Greek games," from Greek periodos "cycle, circuit, period of time," literally "a going around," from peri "around" (see peri-) + hodos "a going, traveling, journey; a way, path, road," a word of uncertain origin (see Exodus).

Sense of "repeated cycle of events" led to that of "interval of time." From 1712 as "an indefinite part of any continued state or series of events;" by 1727 as "time in which a circuit or revolution (as of a heavenly body) is made." Sense of "episode of menstruation" is by 1829, probably short for period of menstruation (1808), etc.  

The meaning "dot marking end of a sentence" is recorded c. 1600, from the earlier sense of "a complete sentence, from one full stop to another," then "a full pause at the end of a sentence" (1580s). The educational sense of "portion of time set apart for a lesson" is from 1876. The sporting sense "division of a game or contest" is attested by 1898. As an adjective from 1905; period piece is attested from 1911.